Water you can trust

How much, and for how long

Ready.gov builds the basic kit around one gallon of water per person per day for drinking and sanitation, for several days. Arizona emergency managers tell households to cover at least 72 hours. That gallon is a planning floor, not a medical prescription. Heat, illness, pregnancy, nursing, and hard work all raise what people actually drink. Pets need their own bowl, not a guess carved out of a person’s gallon.

Three days is the floor. Two weeks is the household aim once you have a cool, dark place to put it. Fourteen gallons a person is heavy. Split the load: factory-sealed bottles you rotate by the date on the package, plus food-grade jugs you refill, plus a way to treat more water if the outage runs long.

• Three-day floor: 3 gallons per person, then add pets.
• Two-week aim: 14 gallons per person if storage allows.
• In desert heat, plan extra drinking water. Do not ration so hard that people stop drinking.
• Keep stored water out of a hot attic. Heat and thin plastic are a bad pair.

If the tap is unsafe or dry

Officials will say whether tap water is safe. Until they do, do not assume a clear glass is a clean glass. CDC’s emergency method starts by letting cloudy water settle and pouring off the clearer part, or straining it through a clean cloth, paper towel, or coffee filter.

Boiling is the most reliable home method CDC describes. Bring clear water to a rolling boil for 1 minute. Above 6,500 feet, boil for 3 minutes. Let it cool, then store it in clean, covered containers.

If you cannot boil, CDC allows unscented household chlorine bleach and nothing fancier. Use regular bleach labeled 5% to 9% sodium hypochlorite. Not scented, not color-safe, not splashless, not with added cleaners. For clear water, the CDC dose is 8 drops per gallon, or about ½ milliliter, or a little less than ⅛ teaspoon. Double that if the water is cloudy, murky, colored, or very cold. Stir and wait 30 minutes. A faint chlorine smell is expected. Bleach kills many bacteria and viruses. It is weaker against parasites such as Cryptosporidium. CDC notes boiling is the stronger step against those.

• Read the percentage on the bottle. A 1% bleach needs a much larger dose. Use the live CDC table, not a number remembered from an old card.
• Pool chemicals and “splashless” bleach are not drinking-water tools.
• A camping filter helps only within its own manual. Many filters do not remove viruses unless the maker says they do.
• Find the main shutoff before you need it. A burst pipe wastes the water you still had.

Containers and rotation

CDC prefers clean, food-grade containers with tight lids, sanitized before you fill them. Never use a jug that held chemicals. Thin milk jugs crack and are hard to clean, so they are a poor long store.

Replace factory-sealed water by the date on the package. The American Red Cross food-and-water sheet says to replace the water every six months if it is not commercially bottled water. Write the fill date on the jug. If you are unsure, use that water for washing and drink water you just treated.